adding documentation about power management
PATCH 1/1 adding documentation about power management
Hi,
this is the first part of added documentation about power management in drivers.
Regards
Oliver
You can import this changeset into BK by piping this whole message to:
'| bk receive [path to repository]' or apply the patch as usual.
===================================================================
[email protected], 2004-10-04 13:50:42+02:00, [email protected]
- adding Documentation about kernel threads and power management
kernel_threads.txt | 41 +++++++++++++++++++++++++++++++++++++++++ 1 files changed, 41 insertions(+)
Documentation/power/kernel_threads.txt new file +41 -0
@@ -0,0 +1,41 @@ +KERNEL THREADS + + +Freezer + +Upon entering a suspended state the system will freeze all +tasks. This is done by delivering pseudosignals. This affects +kernel threads, too. To successfully freeze a kernel thread +the thread has to check for the pseudosignal and enter the +refrigerator. Code to do this looks like this: + + do { + hub_events(); + wait_event_interruptible(khubd_wait, !list_empty(&hub_event_list)); + if (current->flags & PF_FREEZE) + refrigerator(PF_FREEZE); + } while (!signal_pending(current)); + +from drivers/usb/core/hub.c::hub_thread() + + +The Unfreezable + +Some kernel threads however, must not be frozen. The kernel must +be able to finish pending IO operations and later on be able to +write the memory image to disk. Kernel threads needed to do IO +must stay awake. Such threads must mark themselves unfreezable +like this: + + /* + * This thread doesn't need any user-level access, + * so get rid of all our resources. + */ + daemonize("usb-storage"); + + current->flags |= PF_NOFREEZE; + +from drivers/usb/storage/usb.c::usb_stor_control_thread() + +Such drivers are themselves responsible for staying quiet during +the actual snapshotting.
===================================================================
This BitKeeper patch contains the following changesets:
1.2047
## Wrapped with gzip_uu ##
M'XL( %,Y84$ [U6;7/:1A#^S/V*33*3XL3H#2%C,F22V+CQ.&-[L-WIM.DP MA[1"-T@Z>G<RQJ7_O7L"OY"F'9)) @C0[=[>[O,\MZ=G<*51]1HR%]>HV#-X M+[6A6RQEB4XF"\Q%6=TX4DW(.)22C*X==F6>B\"]5(C:G4LU#2)&'N?<Q!E0 M*-UK^$[[?L0L9MAK# <_7WUX.V2LWX>#C)<3O$ #_3XS4EWS/-%ON,ER63I& M\5(7:+@3RV)Y[[H,/"^@=\??:WN=:.E'7KBWC/W$]WGH8^(%83<*V9AK(WCY M9DXAA8.5S?[WNR7^V P7^G1YGM<.HV5[+]R/V"'X3D!QP0M=WW.]$/QVK^/U MPN"E%_0\#U98O?D<1O#2AY;'WL&W+>B Q= "GB2BG,"AC*L"2\.-D"7PL:P, M3%&5F(/)%/)$ R\3F,DY*BAXR2=HW=D)=,*N%[+S!^A9ZPM?C'G<8Z__#X+E M1GYNG8:[RF^TSL\Q-P_8^W[8#;I+HF _6N[M81A%:3OE02<<1\DW7VA_V8Y\
M L$J<+OY5IZG.(=4Y-C;<@Y+ 2%DO]#%?A14M6Z]#=&&W5[0W4:TWO<0;0SO MA#E!G)$,+7CP7WW#W1+4$Z#=>;XM!4/X%T*_@G?3#?RO4/V/9='_.A;#[]1[ MCL G[%?[Y@Q::EY_"):MN?ARP(\]"&G5P?!T\ $NWP\';P\OV$=Z'Y%P;NFD M^LBN9M3^:&U4MBMRT)6>89E@ IKR06J&"'JA#18P%WD.:3T3>)XSP_54.W"9 M"0WT20A,&"\@P1I>&VZFL4JD%I.2YW>>/$TQ-IIM-MM=PEN2AZ0$XABU3JL\
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
Hi!
Quoted 2 lines
this is the first part of added documentation about power management in drivers.
Looks good to me.
Pavel
Am Montag, 4. Oktober 2004 14:28 schrieb Pavel Machek:
Quoted 7 lines
Hi!
Quoted 2 lines
this is the first part of added documentation about power management in drivers.
Looks good to me.
Pavel
Meaning that you'll apply it?
Regards
Oliver
Hi!
Quoted 6 lines
Quoted 4 lines
Quoted 2 lines
this is the first part of added documentation about power management in drivers.
Looks good to me.
Meaning that you'll apply it?
Meaning that you should mail it to Andrew... I do not use bitkeeper, and this kind of docs is probably okay to go directly. You can probably get andrew to just pull from your bk tree, if you promise to only put docs updates there.
Pavel
Signature · 1 line
Boycot Kodak -- for their patent abuse against Java.